This invention relates to twisting and stranding technology for electric or optical cables and lines in general and more particularly to the mechanical design of a driving device by means of which the rotary motion of a rotating twisting head of an SZ stranding machine can be changed periodically between at least three states of motion lasting for intervals, i.e. in several steps.
In driving SZ stranding machines for electric or optical cables and lines it is important, in view of the spacing of the reversal points of the twist direction in the material to be twisted, that the change of the rotary motion of the rotating twisting tool be accomplished as quickly as possible. It is therefore desirable to keep the masses to be reversed as small as possible. One known driving device, described in DE-AS No. 25 16 150, which meets this requirement and has found acceptance in practice, for this purpose, arranges the twisting tool itself and its driving wheels on a common, rotatable hollow shaft, through which the material to be twisted is brought. The driving wheels are rotatably supported on the hollow shaft. A magnetic clutch arranged on the hollow shaft is associated with each drive wheel. The rotor of the clutch is firmly connected to the hollow shaft. It is assumed here that the rotary motion of the twisting head alternatingly takes two different states. Several such twisting heads may be arranged working in parallel, where the speeds and the change in direction of rotation of the twisting heads are controlled by an electronic device ("Wire Journal", 1978, pages 74 to 79).
It is further known to change the rotary motion of the rotating twisting heads of an SZ twisting machine in several steps in order to increase the distances between change in direction of twist in the material to be twisted. The design of the driving device for these twisting heads is not described in detail. (EP-OS 0 004 295).
Starting from a driving device for a twisting head of an SZ stranding machine for electric or optical cables, by means of which the rotary motion of the twisting head is periodically changed in steps, and in which two driving wheels of the twisting head are rotatably supported on a rotatable hollow shaft and a twisting tool itself and the rotor of a magnetic clutch associated with each driving wheel are firmly connected to the hollow shaft, it is an object of the present invention to provide a driving device which ensures, with a small amount of equipment, the rapid reversal of the rotary motion of the twisting head even where the rotary motion is changed between at least three motion states which last for intervals.